The present invention relates to instruments for chemical and biological analyses employing surface plasmon resonance, and in particular, to a portable version of such an instrument suitable for field use.
In surface plasmon resonance imaging, a sensor consisting of a thin metallic film is illuminated by polarized light of an appropriate wavelength and angle of incidence on a “reflecting” side of the film. The energy from the light couples to electrons of the metal of the film creating a resonant condition (surface plasmon resonance) that is highly sensitive to surface conditions on a “sensing” side of the film opposite the side that is illuminated.
Probe molecules are attached to the sensing side of the metallic film to selectively bind with target molecules in a solution to be analyzed. This binding, through the agency of the electron resonance in the film, causes a drop in reflectance of the reflecting side of the film. Detection of the decrease in reflected light thus provides a sensitive measurement of the binding of target molecules to the probe molecules, in turn providing an indication of the content of the solution being analyzed.
By placing a variety of different probe molecules on the sensing surface of the film, many different target molecules may be rapidly assessed. Importantly, the target molecules need not be labeled with fluorescent dye or the like prior to analysis.
Current surface plasmon resonance (SPR) equipment is large, complex, and expensive, and normally confined to use in a laboratory environment. A hand-held SPR device that could be easily transported to the field for remote measurements would be extremely valuable in assessing disease and detecting bio-terrorism and a variety of other analytic uses.